Rates & sources
UK tax rates and thresholds, as published by HMRC. Scotland and Wales have devolved rates for income tax and property transactions.
Source: HMRC — Tax rates — figures refreshed at the start of each tax year.
When to use this calculator
- Before accepting a pay change, bonus, pension contribution, or salary-sacrifice option.
- When you want to compare employed, self-employed, or dividend-based income scenarios.
- When you need a simple take-home estimate before running payroll or filing returns.
- When you are approaching the £100,000 income level and want to understand the personal allowance taper effect.
- When you are planning a salary sacrifice arrangement and need to see the net pay impact before agreeing terms.
A realistic South Africa planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Gross Annual Salary (R)
R400,000
Monthly Sacrifice Amount (R)
6
Income Tax Rate (%)
R400,000
National Insurance Rate (%)
5%
After entering these figures, review annual saving, tax saving and ni saving together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Annual Saving
This gives you the recurring yearly benefit of the change or upgrade, which is usually the most practical starting point when comparing options. Divide it by 12 to see the monthly equivalent, or multiply by 5 to get a five-year view of the cumulative gain.
Tax Saving
Review this figure alongside your gross income so you can understand the true cost of deductions and plan around any thresholds before the tax year closes. If the figure looks higher than expected, check whether any pension or gift-aid contributions could reduce your taxable income.
NI Saving
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Net Monthly Cost
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator estimates the take-home pay and tax savings generated by a salary sacrifice arrangement. It applies current HMRC rules for income tax bands and National Insurance Class 1 contributions, reducing your gross salary by the sacrificed amount before calculating liabilities. The results reflect savings for both employee and employer NI where relevant.
The calculator assumes a standard single-employment scenario in England, Wales, or Northern Ireland. It does not account for Scottish income tax rates, pension annual allowance limits, tapered annual allowance for high earners, or the impact on means-tested benefits such as tax credits or universal credit. Benefit-in-kind values for employer-provided assets are also excluded. Always confirm the figures with your employer's payroll team before making any elections.
Common mistakes
- !Entering gross income when you really want take-home pay, or vice versa.
- !Ignoring pension contributions, deductions, or local tax rules that change the result.
- !Comparing monthly and annual figures without standardising them first.
- !Overlooking the National Insurance threshold changes that apply mid-year when rates or bands are adjusted in a Budget.
- !Assuming a salary sacrifice benefit reduces take-home pay by the full gross amount, rather than only the after-tax cost.
What to do next
- Check the same scenario with related pay or deduction calculators to see the full picture.
- Keep a copy of the assumptions you used so you can compare next tax year or pay period accurately.
- Read the related guides below if you are choosing between multiple income or deduction options.
- If you are self-employed, run the self-employment tax calculator alongside this result to compare the net position against employed income.
- Check whether increasing your pension contribution by even one or two percent changes the take-home significantly — use the pension calculator next.
Frequently asked
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End-of-article next steps
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